Author Topic: 1953 Plunger B33 gearbox oil leak level  (Read 2217 times)

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Mark N

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Re: 1953 Plunger B33 gearbox oil leak level
« Reply #15 on: 26 November, 2019, 12:21:21 »
Iím no expert, but Iím considering trying Deanís clever fix on other models. Or would it only work on an M20? ;D

Christouring

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Re: 1953 Plunger B33 gearbox oil leak level
« Reply #16 on: 18 December, 2019, 22:15:57 »
thank you for all the informative tips, some long term fixes and  some more Heath Robinson .
I am choosing  a variant of Dean's suggestion as my overall Top Tip !!

GeoffRS

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Re: 1953 Plunger B33 gearbox oil leak level
« Reply #17 on: 07 September, 2020, 18:05:07 »
A very late response to an old problem! I also own a 1953 M33 (recent purchase and still getting to grips with the foibles of BSAs and their oil tightness...or not!). I've stripped and rebuilt the gearbox, replacing bearing with modern sealed bearing, retaining the outer side seal. On filling the box with the required one pint and running the engine, oil immediately starts to leak from the output shaft on to the chain. This stops when the oil in the gearbox has dropped to about 2/3 rds of a pint. Being a 1953 plunger model the SRM modified nut doesn't fit. Thickness of oil doesn't seem to make any appreciable difference. Just wondering if there has been any further development with regard to a cure for this issue. Did you ever cure yours Christouring? Either way it looks like the gearbox has to come to bits again!

Jim S

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Re: 1953 Plunger B33 gearbox oil leak level
« Reply #18 on: 08 September, 2020, 03:17:18 »
GeoffRS
See this post:
https://www.bsaownersclub.co.uk/bsaoc_forum/index.php?topic=9041.0
A brief summary:
Put 400ml of oil in the gearbox, or fill to about 1.0 to 1.2 inches below the gearbox main shaft centerline.

martinh10

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Re: 1953 Plunger B33 gearbox oil leak level
« Reply #19 on: 03 October, 2020, 16:32:10 »
I had a similar problem on a plunger B31 I purchased. I established that the oil was coming from between the g/box mainshaft and the pinion sleeve (which carries the g/box sprocket). I eventually resorted to removing the primary chaincase and sliding a 20mm I/D x 2.5mm Viton 'O'Ring onto the mainshaft into the annular vee at the end of the pinion sleeve. The cork and felt washers between the primary chaincase and gearbox firmly press the 'O' ring against the end of the pinion sleeve. I've done a few hundred miles since with no sign of a leak.